JP2003085041A - Disk cache system - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a disk cache system capable of executing startup processing quickly by using data cached in a nonvolatile memory. The disk cache system includes a non-volatile memory and a disk device. When a power supply of the system is turned on, it is detected whether or not a hard disk has been replaced, and data cached in the non-volatile memory becomes valid. It is determined whether or not the data is cached in the non-volatile memory when the data is valid, so that the startup process can be performed even when the spin-up of the hard disk is not completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk cache system, and more particularly to a disk cache system using a non-volatile memory.

[0002]

2. Description of the Related Art Conventionally, a disk cache device using a non-volatile memory has been used to prevent the loss of unwritten data when a power system failure such as a power failure occurs. Therefore, the entire system is backed up by an uninterruptible power supply at the time of a power failure, or the power supply system / controller system is duplicated and a battery backup power supply system is provided to guarantee data.

A disk cache device using a semiconductor memory is used for data transfer between a hard disk and a main memory, and write information and read information from the hard disk are different from those of the main memory. This is a technique for increasing the apparent speed of hard disk access by temporarily storing it in a semiconductor memory.

As a conventional technique of this type, Japanese Patent Laid-Open No. 8-6
In the disk cache device of Japanese Patent No. 3396, a part of the IC memory card is used as a non-volatile memory, and the control information of the disk cache memory is set therein to perform optimum control for the system.

In the semiconductor disk device disclosed in Japanese Patent Laid-Open No. 9-34805, in a semiconductor disk device having a cache memory, a hard disk and a battery, when a battery failure is detected, write data is sent to both the cache memory and the hard disk. I am writing to.

In these prior arts, the semiconductor cache itself, which mainly serves as a cache for disk data, is premised on a volatile memory. With a configuration using such a volatile memory, the power is turned off before the power is turned off. , The contents of the cache must be written back to the hard disk.

In the disk cache device disclosed in Japanese Patent Laid-Open No. 11-45210, an inexpensive and large-capacity non-volatile memory such as a flash ROM is used for the cache, and the contents of the cache are written back to the hard disk before the power is turned off. This improves the apparent disk access performance and improves the usability for the user.

[0008]

However, in recent years, Win
Since high-performance OSs such as Windows (registered trademark) and UNIX (registered trademark) have come to be used, and a shutdown process is indispensable, the write-back cache writes when the normal power off process is performed. It can never be returned. In addition, in recent personal computer systems, the power is automatically turned off when shutdown processing is performed.
The need to reduce the processing when the power is turned off is diminishing.

Considering these backgrounds, when the system is powered off by performing a normal shutdown process, the above-mentioned conventional technique cannot effectively use the non-volatile cache memory.

In addition, as personal computers have come into general use, the time from turning on the power supply to being able to use the personal computer such as home electric appliances, the hibernation, and the return time from Save to Disk are set. The demand for shortening as much as possible (OnNow) is increasing. Therefore, although the CPU execution speed and the memory access speed are sufficiently high,
The hard disk startup time required for booting S, especially the time until spin-up, is becoming a problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a disk cache system capable of promptly executing a boot process by using data cached in a nonvolatile memory. To do.

[0012]

In order to solve the above problems, a disk cache system according to claim 1 of the present invention is a disk cache system comprising a non-volatile memory and a disk device, and the system power is turned on. When the hard disk is replaced, it is detected whether the hard disk has been replaced and whether the data cached in the non-volatile memory is valid or not is determined. Therefore, since the non-volatile memory is used as a cache, the contents of the cache can be used before physically accessing the hard disk even after the power is turned off and the system is restarted. it can. Also, since it is detected that the hard disk has been replaced, it can be confirmed whether the cached data is valid. When the hard disk has been replaced, the cache contents are discarded and the hard disk is accessed to prevent data inconsistency.

According to a second aspect of the present invention, in the disk cache system according to the first aspect, when the hard disk is not replaced immediately after the power of the system is turned on, the cache is stored in the nonvolatile memory. It is characterized in that the booted data can be used even when the spin-up of the hard disk is not completed by using the created data for the boot processing. Immediately after turning on the power,
Since a hard disk needs to increase the rotational speed of the disk to several thousand rpm, it takes a very long time compared to semiconductor devices such as CPU and DRAM, but a nonvolatile memory takes such a time to start up. There is no. Therefore, by using the data cached in the non-volatile memory, the boot process can be executed promptly.

A third aspect of the present invention is characterized in that, in the disk cache system according to the second aspect, data necessary for a start-up process is written in the nonvolatile memory. Therefore, by writing the data required to be cached in the non-volatile memory first at the time of booting the OS, the booting of the OS can be started without waiting for the rotation speed of the hard disk to stabilize. Also, if the hard disk is rotated while the data necessary for initial startup of the OS is read from the non-volatile memory, the time from the power On to the actual disk access is apparently long. Since it is not necessary to rapidly rotate the motor, it is possible to reduce power consumption at startup.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment constituting a disk cache system of the present invention. In FIG. 1, this system includes a CPU 1 and a DRAM.
2, non-volatile memory 3, hard disk 4, Video
Controller6, Video RAM7, C
The computer having the RT 8, the keyboard 9 and the mouse 10 is provided with the exchange detecting mechanism 5. CP
U1 controls the entire system, and controls each circuit connected via the system bus by starting a program. The system bus includes a DRAM 2, a non-volatile memory 3, a hard disk 4, a replacement detection mechanism 5, and V.
videoController6, Video RAM
7, a keyboard 9 and a mouse 10 are connected. DR
AM2 is a volatile memory used as a main memory. Video Controller6 is Vid
The contents of the eo RAM 7 are displayed on the CRT 8. Vid
The eo RAM 7 is a memory that holds the contents displayed on the CRT 8. The keyboard 9 is an input device for giving an instruction to input data. The mouse 10 functions as a pointing device.

The non-volatile memory 3 has a large flash capacity.
It is composed of an EEPROM and functions as a disk cache in this embodiment. In the present embodiment, the flash ROM is used as the non-volatile memory from the viewpoint of cost, mounting area, etc., but a SRAM Card with a built-in battery or the like may be used. The hard disk 4 is an external storage device for storing various data. The replacement detection mechanism 5 is a mechanism that detects whether or not the hard disk 4 has been replaced. Here, the hard disk 4 and the non-volatile memory 3 are connected to the system bus, respectively, but they may all be taken into the disk system. In this case, the replacement detection mechanism 5 is unnecessary.

FIG. 2 is a flow chart for explaining the processing when shutting down the system described above. First, a process of writing back the data cached in the nonvolatile memory 3 is performed (step S10). This process is unnecessary if the non-volatile memory is not used as a write-back cache.

Next, it is confirmed whether or not the data written in the nonvolatile memory 3 needs to be changed (step S11). Similarly, if it is not used as a write-back cache, the process is not necessary because it is not normally changed, but it is necessary when a new OS is installed or when hibernation is executed.

Next, when it is necessary to change the data in step S11, the data required first at the time of booting the OS is acquired and written in the nonvolatile memory 3 and the hard disk 4 (step S12). Non-volatile memory 3
This process is continued as long as there is a free area in the memory and data necessary for booting the OS exists (steps S13 and S1).
4, S17).

If there is data to be written in step S13, but there is no free space in the nonvolatile memory 3,
It is confirmed whether the data on the hard disk 4 side needs to be changed (step S15). When it is necessary to change the data on the hard disk 4, that is, when a new OS is installed or when hibernation is performed, only the hard disk 4 is continuously written (step S16) and the shutdown process is continued. The power is turned off.

FIG. 3 is a flow chart for explaining the processing when the power of the present system is turned on. First, the exchange detection mechanism 5 confirms that the hard disk 4 has not been exchanged (step S20). If the hard disk 4 has been replaced, it cannot be guaranteed that the data on the hard disk 4 and the data stored in the non-volatile memory 3 are the same, so a flag indicating that the data in the non-volatile memory 3 is invalid. Is set, and for subsequent reading, the hard disk 4 is directly accessed (step S21).

In step S20, if the hard disk 4 has not been replaced, the data is read from the non-volatile memory 3. This process is continued as long as valid data exists in the non-volatile memory 3 (steps S22, S23, S2).
4). In step S22, when there is no more necessary data in the non-volatile memory 3, the hard disk 4 is directly accessed for subsequent reading (steps S25, S26, S24, S22).

When the non-volatile memory is used as the write-back cache, it is naturally possible to perform the write processing at the next start-up as in the prior art.

[0024]

As described above, according to the present invention, by using the data cached in the non-volatile memory, the boot process can be executed promptly.

According to the first aspect of the present invention, since the non-volatile memory is used as a cache, the contents of the cache should be used before physically accessing the hard disk even after the power is turned off and the system is restarted. The startup process can be executed promptly. Also, because it detects that the hard disk has been replaced,
You can check whether the cached data is valid. When the hard disk has been replaced, the cache contents are discarded and the hard disk is accessed to prevent data inconsistency.

According to the invention of claim 2, the power source is turned on.
Immediately after n, the hard disk needs to increase the rotation speed of the disk to several thousand rotations per minute.
Although it takes a very long time as compared with a semiconductor device such as AM, the nonvolatile memory does not have such a time required for rising. Therefore, by using the data cached in the non-volatile memory, the boot process can be executed promptly.

According to the third aspect of the invention, by writing the data that is first cached in the non-volatile memory at the time of booting the OS, without waiting for the rotational speed of the hard disk to stabilize. , OS can be started. Also, if the hard disk is rotated while the data necessary for initial startup of the OS is read from the non-volatile memory, the time from the power On to the actual disk access is apparently long. Since it is not necessary to rapidly rotate the motor, it is possible to reduce power consumption at startup.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment constituting a disk cache system of the present invention.

FIG. 2 is a flowchart illustrating processing when shutting down the present system.

FIG. 3 is a flowchart illustrating a process when the present system is powered on.

[Explanation of symbols]

1 ... CPU, 2 ... DRAM, 3 ... Flash ROM, 4
... Hard disk, 5 ... Exchange detection mechanism, 6 ... Video
Controller, 7 ... Video RAM, 8
... CRT, 9 ... keyboard, 10 ... mouse.

Claims (3)

[Claims] 1. A disk cache system comprising a non-volatile memory and a disk device, detects whether a hard disk has been replaced when the system is powered on, and whether the data cached in the non-volatile memory is valid. A disk cache system characterized by making a judgment. 2. The disk cache system according to claim 1, immediately after the power of the system is turned on,
When the hard disk has not been replaced, the data cached in the non-volatile memory is used for the startup processing so that the startup processing can be performed even when the spin-up of the hard disk is not completed. Cache system. 3. The disk cache system according to claim 2, wherein data necessary for start-up processing is written in the nonvolatile memory.